The present invention relates generally, as indicated, to magnetic field analyzers and more particularly to a method and apparatus for measurement of the magnetic field produced by a magnetic sample and preferably by a permanent magnet. The invention is most useful to analyze the magnetic field produced by magnetic sheets.
Typically in measuring a magnetic field, the magnetic property measured is the flux density B in Gauss; one Gauss is one line per square centimeter. In the CGS system, the attractive or pull force F of a magnetic field may be expressed, as follows: EQU F=B.sup.2 A/8.pi. (Equation 1)
wherein the force F is in Dynes, the flux density B is in Gauss, and the area is in square centimeters.
Such force F also can be expressed in terms of average magnetic flux .phi. in Maxwell and area, as follows: EQU F=.phi..sup.2 /8.pi.A (Equation 2)
In the past, accurate instrumentation to measure magnetic fields, the forces produced thereby, and the variation in the forces as a function of the number of magnetic poles in a magnetic sample and of spacing from the sample was not available. Rather, relatively crude fish scale or balance techniques were used to measure the force of a magnet. In the balance technique, the magnet is securely held and a magnetically responsive object is pulled away from the magnet; a balance or scale attached to such object, for example, indicates the force required to pull the same from the magnet. This balance technique is inaccurate due to inaccuracies in the balance and in reading the same, due to possible distortion of the magnet, due to lack of accurate control of the air gap or spacing between the magnet and the object, and so on. Additionally, the fish scale balance technique is incapable of yielding information concerning the number of poles or their arrangement in the magnet.